The European Union has fined eight lenders an unprecedented sum of $2.3 billion on Wednesday for rigging interest rates.

German Deutsche Bank, involved in rigging the Euribor and Japanese yen Tibor rates, was fined a total of $983 million, while the French Societe Generale was fined $605 million for manipulating the European Euribor rate.

British bank RBS, already mired in controversy, was fined $530 million for involvement in cartels which rigged both rates.

The European Commission's anti-trust authorities had never previously imposed such big fines overall, the Competition Commissioner, Joaquin Almunia, told a press conference.

In total, four financial institutions were involved in a cartel which rigged the Euribor rate and six in a cartel which manipulated the Tibor rate.

In the Euribor case, British bank Barclays benefited from immunity and will not pay a fine because it revealed the existence of the rigging to the Commission.

The investigations and fines come after a separate scandal broke over the rigging of the London Libor rate which is used as a benchmark for many types of financial contracts around the world.

The Euribor, Tibor and Libor interest rates are calculated slightly differently, but fulfill a vital function as a reference for the rates which banks are charging to lend each other.

Contracts covering a vast range of financial instruments and vast amounts of money depend in part on the interest rates indicated by Euribor, Tibor, and Libor.